In a small skillet, melt butter over medium heat until it starts to bubble and emit a pleasant nutty aroma - remove from heat and let cool slightly.

In a large bowl, add melted butter and sugars - whisk until combined. Whisk in eggs and vanilla.

Add the flour and salt into the large bowl and mix just until combined. Add about half of each of the chocolate and cinnamon chips - fold into the batter. Scoop the mixture into a 9" by 13" baking dish coated with nonstick spray - use an off-set spatula to spread the batter evenly and smooth the top. Scatter the remaining remaining chips on top and lightly press to adhere.

Bake until golden and a toothpick placed near the center comes out with a few moist crumbs attached - about 35 to 45 minutes. Remove and let cool on a wire rack before cutting into squares.